The amount of oxalate absorbed from ingested foods in the intestine has the potential to make a substantial contribution to urinary oxalate excretion and be a significant risk factor for the onset of calcium oxalate kidney stones. The hypothesis being tested in this project is that the amount absorbed is dependent on the amounts of oxalate and calcium in the intestine and the fraction of free oxalate anion. The oxalate content of foods is being measured by capillary electrophoresis and diets with known contents of oxalate, calcium and other important ions developed. Normal volunteers will consume these diets to determine the dependency of urinary oxalate excretion on the amounts of oxalate and calcium ingested and the free anion in intestinal contents. These studies should reveal the importance of these variables in influencing urinary oxalate excretion.